chore: bump doc requirement complained by dependabot

Author: dvarrazzo

doc/requirements.txt

@@ -46,5 +46,5 @@ sphinxcontrib-qthelp==1.0.3
     # via sphinx
 sphinxcontrib-serializinghtml==1.1.5
     # via sphinx
-urllib3==1.26.15
+urllib3==1.26.17
     # via requests